Chapter 3 - Stoichiometry Flashcards
What is molecular formula?
Molecular formula is the number and type of different atoms in one molecule. The molecular formula for an ionic compound is always in its empirical formula.
What is empirical formula?
Empirical formula is the simplest whole number ration of the different atoms or ions in a compound.
How do you show a chemical reaction?
Reactants ⟶ products
What are state symbols?
State symbols include solid (s), liquid (l), gas (g) and aqueous (aq). Precipitates formed in solution count as solids.
What is relative atomic mass?
The symbol for relative atomic mass is Ar. The relative atomic mass is the larger number shown on the periodic table. The relative atomic mass is defined as the average mass of the isotopes of an element compared to 1/12th the mass of an atom of 12C.
What is relative molecular mass?
The symbol for the relative molecular mass is Mr. Relative molecular mass is defined as the sum of the relative atomic masses. Relative molecular mass will be used for ionic compounds
What is a mole?
The mole, mol, is the unit of amount of substance. One mole contains 6.02x1023 particles. This number is the Avogadro constant. The mass of one mole is known as the molar mass. This is the same as the relative atomic mass for an element or the relative molecular mass for a compound.
Moles = mass / molar mass
Formulas for (moles, mass and molar mass), (moles, concentration and volume) and (number of particles, moles and avogardos number)
What is the volume occupied by one mole of gas?
Avogadro’s law states that at the same temperature and pressure, equal amounts of gases occupy the same volume of space. At room temperature and pressure, the volume occupied by one mole of any gas was found to be 24dm3 or 24,000cm3
Formula for volume, moles and molar volume (24dm3/mol)
Formula for moles, volume in dm3 and concentration
How do you measure concentration?
Concentration can be measured in g/dm3 or mol/dm3.
How do you convert between dm3 and cm3?
Dm3 x 10^3 (1000) = cm3
What is the limiting reactant and the excess reactant?
The reactant that is used up first is the limiting reactant. The one that is remaining is the excess reactant.
How do you determine the limiting reactant?
When determining the limiting reactant, you firstly convert the mass of each reactant into moles, write the balanced equation and determine the molar ratio and look at the equation and compare the moles.
How is a solute and solution measured?
The solute is measured in grams (g) or moles (mol). The solute is measured in cm3 or dm3. A solution is measured in cm3 or dm3.
How do you calculate empirical formula?
Write the element, write the value for each elements (mass or percentage), write the relative atomic mass of each element, calculate the moles, calculate the ratio of the elements by dividing them all by the smallest number of moles, if you don’t get whole numbers you multiply them by an appropriate number to get all the values into whole numbers and finally write the empirical formula.
How do you calculate molecular formula?
Find the relative formula mass of the empirical formula, use the following formula: relative formula mass of molecular formula / relative formula mass of empirical formula
Multiply the number of each element present in the empirical formula by the number from step 2 to find the molecular formula.
What is yield?
Yield is the term used to describe the amount of product you get from a reaction.
What is percentage yield?
Percentage yield compares the actual yield to the theoretical yield.
What is actual yield?
Actual yield is the recorded amount of the product obtained.
What is theoretical yield?
Theoretical yield is the amount of product that would be obtained under perfect practical and chemical conditions.
What is percentage composition?
Percentage composition of any compound is the way to express the mass of each element as a percentage of the total mass of the compound.
What is percentage purity?
